This project uses data from the third National Health and Nutrition Examination Survey (NHANES III, 1988-94), linked to birth certificates for sample children ages 2-83 mo (coordinated by Dr. Overpeck through an interagency agreement with NCHS/CDC) to explore the health consequences of intrauterine growth. The latest analyses have focused breast-feeding, motor and social development (MSD), and early childhood caries (ECC). Analyses have been completed related to infant feeding and MSD, and have been initiated for ECC. We addressed whether infants exclusively breast-fed for 4 mo differed in size from infants fed other ways, and whether such differences persist through age 5 y. While infants exclusively breast-fed for 4 mo weighed less at 8-11 mo (p<0.05), there were few significant differences in growth after the first year related to early infant feeding. Since it has also been suggested that breast-feeding is protective against overweight in children and that there is a dose-dependent effect of its duration, children ages 3-5 y were categorized by body mass index (kg/m2) as being overweight (OW95, > 95th percentile) based on cutoffs from the new NCHS growth charts. Adjusting for confounders, there was no significant reduced risk of being OW95 (AOR=0.90, 95% CI=0.67-1.21) and no clear dose-dependent effect of the duration of full breast-feeding. Breast-feeding continues to be strongly recommended, but may not be a leading indicator for the prevention of overweight in early childhood. In other analyses, we determined the independent effects of birth weight and gestational age on MSD, using an age-appropriate scale from 2-47 mo. Three percent of the infants and children were born preterm LBW and 2.2% term LBW. Adjusting for confounders, preterm LBW children still had lower MSD scores (-1.5?0.3 points, p<0.0001), as did term LBW children (-0.8?0.4 points, p<0.03). LBW status and preterm delivery were associated independently with small, but measurable delays in MSD through early childhood. Even for children only moderately LBW or moderately preterm, perinatal factors should be considered in association with other known risk factors for development delays in determining the need for clinical follow-up and evaluation.